This invention relates to a semiconductor device, and more particularly to a evaporation-boiling cooling type semiconductor device providing freon (TM) as a cooling medium.
There is a semiconductor device which accommodates a semiconductor body and freon as a cooling medium and the generated heat of the semiconductor body is cooled by vaporization under evaporation-boiling of the freon.
In usual operation of a such semiconductor device, pressure in the vessel caused by a vaporization of the freon while absorbing heat of the semiconductor body is maintained at positive pressure sufficiently higher than a pressure outside of the vessel i.e., atmosphere.
Accordingly, in this condition, even through leakage exists in the sealed vessel, the atmosphere does not invade the sealed vessel.
However, when the semiconductor does not operate for some cause, the heating of the semiconductor body does not exist, and since the vaporization of freon does not occur, pressure in the vessel will become negative and it is smaller than the atmosphere.
Therefore, the atmosphere invades the vessel if the leakage exists in the sealed vessel when the commercial power fails.